JPH0416640Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a servo motor drive circuit using a reversible electric motor which is driven in forward rotation when a forward rotation switch is turned on and reversely driven when a reverse rotation switch is turned on.

<Prior art> Figure 4 shows a conventional servo motor drive circuit.
In the figure, reference numeral 1 denotes a reversible electric motor, which is configured to rotate in the forward direction when a switch 2 for forward rotation is turned on, and to drive in the reverse direction when a switch 3 for reverse rotation is turned on. 4 is a potentiometer that detects the current position B of the electric motor 1, and 5 is a comparison circuit that compares the detection signal _B1 of the potentiometer 4 with the command signal _A1 that indicates the target position A at which the electric motor 1 should be stopped. .
Reference numeral 6 designates a switch control circuit for controlling the switches 2 and 3 on and off, which inputs the output signal _S1 of the comparison circuit 5 and a setting signal _k1 for setting the dead zone level Δk.
The switches 2 and 3 are controlled on and off so that the motor 1 is driven in the forward or reverse direction until the difference between the target position A and the current position B falls within the dead zone level Δk shown in FIG. Then, the detection signal B ₁ of the potentiometer 4 is compared with the command signal A ₁ indicating the target position A, and either the switch 2 or 3 is turned on to drive the motor 1 to rotate to the target position. It is stopped at this rotational position.

<Problems to be Solved by the Invention> However, in the conventional method, if the width of the dead band level Δk in the switch control circuit 6 is small, the forward/reverse rotation electric motor 1 will cause a hunting phenomenon and will not be able to stop smoothly. In addition, the accuracy normally required for a servo motor is one that has an accuracy of 1/100 or more, and generally has an accuracy of 1/300 or more, but if the dead band level Δk is too wide, the setting accuracy will be reduced. Unfortunately, there is a problem that the function as a servo motor cannot be satisfied.

In view of the above-mentioned problems, the present invention is designed to make it possible to stop at the target position A smoothly and accurately without causing the hunting phenomenon.

<Means for solving the problem> The technical means of the present invention for solving this technical problem is a reversible electric motor that is driven in the forward direction when the forward rotation switch 15 is turned on and reversely driven when the reverse rotation switch 16 is turned on. 11, a potentiometer 21 that detects the current position B of the electric motor 11, a detection signal B1 of the potentiometer ₂₁ , and a command signal _A1 that indicates the target position A at which the electric motor 11 should be stopped.
and a comparator circuit 22 that compares the output signal _S1 of the comparator circuit 22 to the switches 15 and 16 so that the difference between the current position B and the target position A is reduced to the range of the dead zone level Δk. In a servo motor drive circuit including a switch control circuit 24 for on/off control, when the difference between the current position B and the target position A reaches a deceleration range m near the target position including before and after the dead zone level Δk, the reversible electric motor An intermittent control circuit 28 is provided which intermittently controls the switches 15 and 16 which are in the on state so as to decelerate the comparator circuit 2.
The intermittent control circuit 28 includes comparators 25 and 26 that input the output signal S ₁ of 2 and detect that the difference between the current position B and the target position A is within the range of the dead zone level Δk. Comparators 29 and 30 input the output signal _S1 of 22 and detect that the difference between the current position B and the target position A is within the deceleration range m.
When the comparators 29 and 30 detect this, the switches 15 and 16 are activated to decelerate the reversible electric motor 11.
and an oscillation circuit 33 that outputs an intermittent signal.

<Operation> For example, when the target position A is on the forward rotation side of the motor ₁₁ than the current position B as shown in FIG. Since it is on the forward rotation side compared to position B, the forward rotation side comparator 25 outputs the normal rotation signal _D1 , and the intermittent control circuit 28 outputs a high voltage drive signal. As a result, a high voltage is constantly output from the AND circuit 35, the forward rotation switch 15 is turned on by turning on the transistor 18, the forward rotation motor 11 is driven to rotate in the forward direction, and the current position B approaches the target position A. When the current position B reaches within the deceleration range m, the intermittent control circuit 28 outputs an intermittent signal _k1 that repeatedly turns on and off, so that the transistor 18 and the forward rotation switch 15 are turned on and off, and the forward rotation motor 11 is decelerated.
When the current position B reaches within the dead zone level Δk, the switch control circuit 24 stops outputting the forward rotation signal _D1 , so the transistor 18 and the forward rotation switch 15 are turned off, and the driving of the forward rotation motor 11 is stopped. .

Further, when the target position A is on the reverse side of the current position B, the electric motor 11 is first driven in the reverse direction in the same way as above, and when the current position B reaches the deceleration range m, the electric motor 11 is decelerated by intermittent control. Thereafter, when the current position B reaches within the dead zone level Δk, the driving of the electric motor 11 is stopped.

By the way, in order to increase the setting accuracy, it is necessary to widen the deceleration range m and to reduce the intermittent signal _k1 .
DUTY (shorten the ON period), the purpose can be achieved, but if the deceleration range m is made larger than necessary and the intermittent DUTY of the intermittent signal _k1 is made large, the accuracy may be good, but the motor 11 will not reach the target position A. It takes a very long time to reach this point, making it impractical. Therefore, there is a practical limit to the deceleration range m and intermittent DUTY.
As a result of determining this through experiments, as shown in Figure 3, it was found that the deceleration range m in the practical range is 2.5 to 4 times the dead zone level Δk, and that the best accuracy can be achieved with an intermittent duty of 10 to 30%. .

<Embodiment> Hereinafter, the present invention will be explained according to the illustrated embodiment. In FIG. 1, 11 is a reversible electric motor;
2 and 13 are a pair of windings, and 14 is a capacitor. 15 is a switch for forward rotation, 16 is a switch for reverse rotation, and 17 is an AC power supply.
The power supply phase is reversely connected by the on/off control of 6, and the reversible motor 11 is turned on by turning on the forward rotation switch 15.
The reversible electric motor 11 is configured to rotate in the forward direction and to rotate in the reverse direction when the reverse switch 16 is turned on. The switches 15 and 16 are each formed of a photocoupler, and the forward rotation switch 15 is turned on when the transistor 18 is turned on, and the reverse rotation switch 16 is turned on when the transistor 19 is turned on.

Reference numeral 21 denotes a potentiometer mechanically connected to the electric motor 11, which detects the rotational position of the electric motor 11 and outputs a detection signal _B1 indicating the current position B of the electric motor 11 based on voltage. 22 is a comparison circuit that compares the detection signal _B1 of the potentiometer 21 and the motor 11.
A command signal _A1 indicating the target position A at which to stop is input by the magnitude of voltage, and these two signals are compared and an output signal _S1 having a voltage proportional to the difference is output. This output signal S ₁ is, for example, a command signal A ₁
voltage is greater than the voltage of detection signal B ₁ , motor 1
If the motor 1 should be rotated in the forward direction, the voltage will be positive. Conversely, if the voltage of the command signal A ₁ is smaller than the voltage of the detection signal B ₁ and the motor should be driven in the reverse direction, the voltage will be negative.

A switch control circuit 24 controls the switches 15 and 16 on and off, and includes a forward rotation comparator 25 and a reverse rotation comparator 26. The normal rotation comparator 25 inputs the output signal S ₁ of the comparison circuit 22 and the setting signal k ₁ for setting the dead zone level Δk, and when the output signal S ₁ of the comparison circuit 22 is larger than the setting signal k ₁ on the positive side. Forward rotation signal
_D1 is output to the AND circuit 35. The reversing comparator 26 inputs the output signal S ₁ of the comparison circuit 22 and the setting signal k ₁ that sets the dead zone level Δk, and when the output signal S ₁ of the comparison circuit 22 is larger on the negative side than the setting signal k ₁ . Then, the reversal signal _D2 is output to the AND circuit 36.

28 is an intermittent control circuit that controls the switches 15 and 16 intermittently, and includes comparators 29 and 30 and a diode 3.
1 and 32 and an oscillation circuit 33. Oscillation circuit 3
3 divides the power supply cycle to obtain an intermittent signal _h1 that repeats high voltage and low voltage at regular intervals, and comparator 29,
30 inputs the output signal _S1 of the comparator circuit 22, and also inputs the deceleration point setting signal _i1 that variably sets the deceleration range m (see Fig. 2) in the vicinity of the target position including before and after the dead zone level Δk. Intermittent control circuit 28
outputs a drive signal that is always at a high voltage when the current position B is outside the deceleration range m shown in FIG. The intermittent signal h ₁ is output to the AND circuits 35 and 36 at the same time.

<Effect of the invention> According to the invention, the reversible motor 11 is decelerated when the difference between the current position B and the target position A reaches the deceleration range m in the vicinity of the target position including before and after the dead zone level Δk. The switch 1 in the on state
Since an intermittent control circuit 28 is provided for intermittent control of the motors 5 and 16, when the forward rotation switch 15 or the reverse rotation switch 16 is turned on, the rotation is driven from the current position B toward the target position A, and the deceleration range m near the target position is At the point reached, switches 15 and 16 are in the on state.
The electric motor 11 is decelerated by the intermittent operation. Therefore, when the rotational position of the electric motor 11 reaches the range of the dead zone level Δk of the target position A, the driving of the electric motor 11 is stopped, and the electric motor 11 can be stopped quickly without being subjected to a large inertial force. Therefore, by reducing the dead zone level Δk, the electric motor 11 can be stopped smoothly and accurately without causing a hunting phenomenon at the target position A.

Further, the switch control circuit 28 is connected to the comparison circuit 22.
Input the output signal _S1 of the current position B and target position A.
The intermittent control circuit 28 is provided with comparators 25 and 26 that detect that the difference between the current position B and the target position _A is within the range of the dead zone level Δk. comparators 29, 30 detecting that the difference between the
When the comparators 29 and 30 detect this, the switches 15 and 16 are activated to decelerate the reversible electric motor 11.
Since the comparators 25 and 26 are provided with an oscillation circuit 33 that outputs an intermittent signal, it is easily detected from the detection signal _B1 of the potentiometer 21 whether the current position B is within the range of the dead zone level Δk. The current position B can be determined by the comparators 29 and 30.
It can be easily detected from the detection signal _B1 of the potentiometer 21 whether or not it is within the deceleration range m. Therefore, the range of the dead band level Δk and the deceleration range m
There is no need for a position detection switch or the like to detect the dead zone level Δk and the deceleration range m using the same potentiometer 21 and comparison circuit 2.
2 can be used both for detecting the range of the dead zone level Δk and for detecting the deceleration range m, the number of constituent members can be reduced accordingly, and the entire servo motor drive circuit can be made into a simple structure and manufactured at low cost and easily. Furthermore, by changing the setting signals to the comparators 25 and 26 and the comparators 29 and 30, the range of the dead band level Δk and the deceleration range m can be easily varied, which is very convenient in terms of handling and practical use. The effect is significant.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention;
The figure is an explanatory diagram for explaining the operation of the electric motor.
The diagram shows the stopping accuracy of the motor, the deceleration range m, and the intermittent
FIG. 4 is a circuit diagram showing a conventional example. DESCRIPTION OF SYMBOLS 11... Reversible electric motor, 15... Switch for forward rotation, 16... Switch for reverse rotation, 21... Potentiometer, 22... Comparison circuit, 28... Intermittent control circuit.

Claims (1)

[Scope of utility model registration request] A reversible electric motor 11 that rotates in the forward direction when the forward rotation switch 15 is turned on and rotates in the reverse direction when the reverse rotation switch 16 is turned on; a potentiometer 21 that detects the current position B of the electric motor 11; Detection signal B ₁ and motor 1
A comparison circuit 22 compares the command signal A 1 indicating the target position A at which the motor ₁ should be stopped, and an output signal S ₁ of the comparison circuit 22 is inputted to compare the current position B and the target position A.
In the servo motor drive circuit, the servo motor drive circuit includes a switch control circuit 24 that controls the switches 15 and 16 on and off so that the difference between the current position B and the target position A is reduced to a dead band level Δk.
When the difference between the
An intermittent control circuit 28 is provided which intermittently controls the switches 15 and 16 which are in the on state so as to decelerate the speed of the comparator circuit 22.
Input the output signal _S1 of the current position B and target position A.
The intermittent control circuit 28 is provided with comparators 25 and 26 that detect that the difference between the current position B and the target position _A is within the range of the dead zone level Δk. comparators 29, 30 detecting that the difference between the
When the comparators 29 and 30 detect this, the switches 15 and 16 are activated to decelerate the reversible electric motor 11.
and an oscillation circuit 33 that outputs an intermittent signal.